A valve opening/closing timing control apparatus includes: a driving side rotational body synchronously rotating with a crankshaft of an internal combustion engine; a driven side rotational body arranged in the driving side rotational body to share a rotational axis therewith and integrally rotating with a camshaft; advanced angle and retarded angle chambers defined between the driving side and driven side rotational bodies; a lock mechanism maintaining a relative rotational phase between the driving side and driven side rotational bodies by separately biasing first and second lock members to be engaged with first and second recesses; and a fluid controller releasing the locked state by supplying a hydraulic fluid to the first and second recesses, and controlling the relative rotational phase by supplying and discharging the hydraulic fluid to the advanced angle and retarded angle chambers.